PROJECT SUMMARY/ABSTRACT Preeclampsia (PE) is a hypertensive, multi-system disorder of pregnancy that significantly impacts maternal and infant morbidity/mortality across the globe, as it increases risk of cardiovascular disease and remains a leading killer of women and babies. Despite PE?s significant impact on morbidity/mortality, there are no clinically reliable biomarkers that predict PE. The long-term goal of our research is to (1) identify biologic underpinnings and clinically useful, cost efficient biomarkers that predict PE before clinical onset, and (2) to use this information to inform the development of personalized interventions that either prevent PE or halt its progression. DNA methylation, a dynamic regulator of gene expression, represents a mechanism that is known to be impacted by the environment. Because PE stems from a dysfunctional placenta that releases debris into the maternal circulation, we hypothesize that the in vivo environment created by the dysfunctional placenta will impact DNA methylation in the maternal circulation, and that these blood-based methylation profiles will serve as a systemic biomarker of the maternal response to placental dysfunction. Our overall objective of this pilot study is to longitudinally characterize DNA methylation profiles across the three trimesters of pregnancy in the maternal blood at time points before and after clinically overt PE. Aim 1 will use a candidate pathway approach to characterize DNA methylation profiles of the ENG pathway in the maternal blood in women who do and do not develop PE. Aim 1 is focused on the ENG pathway of genes, which was selected based on our preliminary genetic association data to date. Aim 2 is designed to expand the scope of our investigation with the use of a genome-wide, discovery-based approach. We will explore blood-based methylome data to identify gene-based regions and biological pathways that experience site-specific changes across pregnancy and impact pregnancy outcome (PE vs no PE). A key to the success of this project is that we have access to stored DNA specimens extracted from 1st, 2nd, and 3rd trimester peripheral blood samples in women who did and did not develop PE, as well as extensive phenotype data. This project is novel and innovative, as it uses a longitudinal approach to characterize DNA methylation profiles in the maternal blood across pregnancy in women who do and do not develop PE. The ability to assess DNA methylation profiles before and after the onset of clinically overt PE will aid in the identification of novel biomarkers. Moreover, we will be able to identify the orchestration of gene regulation for key biological pathways leading up to PE. This critical information will provide valuable insight into the proximate pathophysiology of the disorder and a how a women systemically responds to the dysfunctional placenta. Furthermore, data generated from this pilot study will be used to support a larger prediction study that is designed to determine the utility of using DNA methylation profiles in the maternal blood as biomarkers of PE across different time points in pregnancy, with the intention that improved understanding of the biological underpinnings of PE will translate into evidence-based interventions that optimize outcomes.